Maybe, at least, the NPCs could be drawn to the items (like the villagers are) so that could be a way to transport them, for example, and have certain classes of NPCs tied to the items, such as the Old Fisherman being tied to the barrel, a Poké Ball vendor tied to the smithing table, a Curry Ingredient vendor tied to the smoker, a medicine vendor tied to the brewing stand, etc.
They could even be used to sell some items that are tied to vanilla mobs such as leather, ender pearls, gunpowder, etc. Yes, I know we can get those by defeating wild Pokemon, but it could also be an alternative.